Dielectrophoresis refers to a phenomenon in which a substance placed in a non-uniform electric field is driven by the interaction between the electric field and a dipole moment induced by the electric field. Research is currently proceeding utilizing this phenomenon in various fields especially in regard to the separation and identification of biological samples. For example, refer to the following literature:    H. Li and R. Bashir, “Dielectrophoretic separation and manipulation of live and heat-treated cells of Listeria on microfabricated devices with interdigitated electrodes”, Sensors and Actuators B: Chemical, vol. 86, no. 2-3, pp. 215-221, 2002.    P. Gascoyne, J. Satayavivad and M. Ruchirwat, “Microfluidic approaches to malaria detection”, Acta Tropica, vol. 89, pp. 357-369, 2004.
Although measurement of the driving force, i.e., the dielectrophoretic force, produced in a specific substance is extremely important, obtaining a concrete numerical value of the force is not easy. Generally, since it is nearly impossible to determine analytically a dielectrophoretic force produced by designed electrodes, the force is found by calculation using the finite element method. This method, however, does not measure the actual dielectrophoretic force.